Fabricating semiconductor devices such as logic and memory devices typically includes processing a substrate such as a semiconductor wafer using a number of semiconductor fabrication processes to form various features and multiple levels of the semiconductor devices. For example, lithography is a semiconductor fabrication process that involves transferring a pattern from a reticle to a resist arranged on a semiconductor wafer. Such patterns may be repeatedly transferred to multiple different locations or “die” or a wafer using a lithography tool known as a “stepper”.
Advanced techniques are often used in conjunction with lithography to help form the proper shapes of features of the device that are small compared to the wavelength of light used in the lithography. One of these advanced techniques is known as “Optical Proximity Correction” (OPC). In OPC local regions of the geometry to be printed are modified on the reticle to correct for known errors that are expected to occur during lithography.
It is within this context that embodiments of the present invention arise.